"Al-Qaeda and associated extremist groups have a wide variety of potential agents and delivery means to choose from for chemical, biological, radiological or nuclear attacks," the US Central Intelligence Agency said in a report obtained by AFP Tuesday.

The report -- entitled "Terrorist CBRN: Materials and Effects," referring to chemical, biological, radiological and nuclear weapons -- noted that several al-Qaeda-associated groups have tried to carry out attacks in Europe "with easily produced chemicals and toxins best suited to assassination and small-scale scenarios." A US official, speaking on condition of anonymity, said the report contained information that had been available "for years" and was merely intended as a "reference tool."

The unclassified report -- dated May 2003 -- noted that a review of an al-Qaeda document found in Afghanistan last summer "indicates the group has crude procedures for making mustard agent, sarin and VX."

It also pointed to training videos uncovered in Afghanistan, which show al-Qaeda's tests of cyanide-based chemical agents.

And the report added that radiological dispersal devices, or so-called "dirty bombs," are also within reach of al-Qaeda because the components are fairly easy to acquire within industry and the medical community.

Monday, the White House said Group of Eight leaders meeting in Evian, France had endorsed a US-engineered plan to thwart terrorist efforts to manufacture dirty bombs and shoot down passenger jets with shoulder-launched missiles.

The move follows a failed November 2002 attempt to down an Israeli airliner in Kenya.

G8 leaders agreed to adopt strict national controls on the export of shoulder-launched missiles and components, the White House said in a statement.

The leaders also promised to help countries that wish to dispose of surplus stocks.

In addition, they agreed to move against dirty bombs -- conventional explosive devices laced with radioactive material -- just over a year after American Jose Padilla was arrested in Chicago and accused of plotting an attack with such a bomb.

The CIA said it believed al-Qaeda also "has explored the possibility of using agricultural aircraft for large-area dissemination of biological warfare agents such as anthrax."

And it added that the group has "openly expressed its desire to produce nuclear weapons.

"We know that the group could easily construct a radiological dispersal device, ... which, while incapable of causing mass radiation-related casualties, could result in panic and enormous economic damage."

It said al-Qaeda aims to use these types of weapons "to cause mass casualties," but it added that "most attacks by the group -- and especially by associated extremists -- probably will be small scale, incorporating relatively crude delivery means and easily produced or obtained chemicals, toxins or radiological substances."

Patrick Garrett, an associate analyst with the GlobalSecurity.org think tank, said al-Qaeda's radiological abilities are "serious."

But he downplayed the imminence of any chemical, biological or nuclear attack by the terror network.

He said the group has a "demonstrated capability" for chemical and biological weapons -- largely "psychological" weapons designed to scare a large number of people -- but stressed: "The question is whether or not al-Qaeda has the ability to deliver those weapons."

"If they had a full capability and the ability to deliver the weapon -- whether it's chemical, biological or nuclear -- if they're as bad as we all believe that they are, why haven't they used it?" Garrett asked.

US, Britain face mounting allegations of deliberate overplaying of Iraqi threat
The United States and Britain face mounting allegations that they deliberately overplayed the Iraqi threat to justify going to war.

Some even say the coalition manipulated intelligence analysis.

The international chorus of criticism is being fuelled by the failure of American forces to find any of the weapons of mass destruction which were cited as the primary reason for the invasion.

Much of the fire is coming from abroad but the controversy is also now gaining ground in the US itself.

Almost two months after Saddam Hussein's statue was toppled in Baghdad, there is still no sign of any Iraqi chemical or biological weapons.

Patrick Garrett, Senior Fellow, GlobalSecurity.org, said: "The credibility of the administration really is at stake at this point."

At stake, because Washington's detailed pre-war case against Iraq left no room for doubt.

On February 5 for instance, US Secretary of State Colin Powell said: "We know Saddam Hussein is determined to keep his weapons of mass destruction, is determined to make more."

But fears that Iraq would use those weapons in the war proved unfounded and no stockpiles have turned up since.

Even strong supporters of the military action are somewhat surprised.

Gary Schmitt, Executive Director, Project for the New American Century, said: "10 years of practising how to hide things is going to mean that things are pretty well hidden. That said, I think people did expect to find some caches of weapons stocks that they haven't found yet."

So far, the best evidence the US has produced are special trucks said to have been mobile biological weapons labs of the sort outlined by Colin Powell at the UN.

The longer the search goes on though, the more sceptical analysts become.

Mr Garrett of GlobalSecurity.org said: "Ideas or arguments that the Bush administration really kind of cooked the books on this one, to create the evidence necessary to justify their political intentions or military strategies, really I think that those arguments are to some extent justified."

The prime backers of the war now find themselves on the defensive.

British Prime Minister Tony Blair said: "The idea that we doctored such intelligence is completely and totally false. Every single piece of intelligence that we presented was cleared very properly by the Joint Intelligence Committee."

But there is even criticism coming from inside the intelligence community itself.

Some serving and recently retired American officials accuse the Bush administration of distorting the evidence.

As the controversy builds, the Bush administration's position seems to be shifting.

Senior officials now say that Iraq may have destroyed its stockpiles and planned to rely instead on carefully hidden production facilities that could be started up when the need arose.